Stemming bag

ABSTRACT

A blasting shot hole stemming bag to be filled with a noncompressible fluid and having a self-closing valve. The valve is formed of overlying strips of vinyl heat sealed along predetermined lines to provide a narrowed valve passage. The bag is fabricated of different thickness or different degrees of flexibility of the plastic vinyl or similar material and has heat seal lines forming the permanently closed end as well as the narrowed filler valve between the bag side walls, and additional heat seal lines restricting the bag top to a small mouth leading to the valve, the valve and valve passage being located within the bag and spaced substantially from the bag mouth to prevent objects from contacting the valve and accidentally opening it. By fabricating the bags so that opposite sides are of the material having the different degrees of flexibility, when filled with the fluid the more flexible bag side is pulled to a greater degree both longitudinally and laterally being evidenced by a pronounced direction of the side and end seams, with the attendant advantage that the bag material at the valve end of the bag is pulled downwardly in a very positive manner to provide a protective shield for the valve to preclude inadvertant opening of the valve during tamping into the shot hole. The bag material is further possessed of a stretchable characteristic enabling the bags to be elongated to reduce their cross-sectional dimension to facilitate their being placed into irregular size shot holes which may result from use of worn drill bits. Multiple bags, each with its valve, may be simultaneously formed by overlying suitable plastic strips and sheets, and forming heat seals along predetermined lines. Individual bags may be torn from the composite sheet by tearing along certain heat seal lines.

United States Patent [191 Marshall Apr. 23, 1974 STEMMING BAG [76]Inventor: Thomas D. Marshall, Box 87,

Prosperity West, Va. 25909 H [22] Filed: Aug. 23, 1972 [21] Appl. No.:282,908

Related US. Application Data [63] Continuation-impart of Ser. No.81,776, Oct. 19,

1970, abandoned.

Primary ExaminerWilliam 1. Price Assistant Examiner-Stephen P. GarbeAttorney, Agent, or Firm-John E. Becker [57] ABSTRACT A blasting shothole stemming bag to be filled with a non-compressible fluid and havinga self-closing valve. The valve is formed of overlying strips of vinylheat sealed along predetermined lines to provide a narrowed valvepassage. The bag is fabricated of different thickness or differentdegrees of flexibility of the plastic vinyl or similar material and hasheat seal lines forming the permanently closed end as well as thenarrowed filler valve between the bag side walls, and additional heatseal lines restricting the bag top to a small mouth leading to thevalve, the valve and valve passage being located within the bag andspaced substantially from the bag mouth to prevent objects fromcontacting the valve and accidentally opening it. By fabricating thebags so that opposite sides are of the material having the differentdegrees of flexibility, when filled with the fluid the more flexible bagside is pulled to a greater degree both longitudinally and laterallybeing evidenced by a pronounced direction of the side and end seams,with the attendant advantage that the bag material at the valve end ofthe bag is pulled downwardly in a very positive manner to provide aprotective shield for the valve to preclude inadvertant opening of thevalve during tamping into the shot hole. The bag material is furtherpossessed of a stretchable characteristic enabling the bags to beelongated to reduce their cross-sectional dimension to facilitate theirbeing placed into irregular size shot holes which may result from use ofworn drill bits. Multiple bags, each with its valve, may besimultaneously formed by overlying suitable plastic strips and sheets,and forming heat seals along predetermined lines. Individual bags may betorn from the composite sheet by tearing along certain heat seal lines.

10 Claims, 9 Drawing Figures PATENTEDAPR 2 m4 3; 806; 025

SHEET 1 0F 2 INVENTOR THoMAs D. MARSHAL.

ATTORNEYS PATENTED APR 2 3 i974 SHEET 2 OF 2 STEMMING BAG BACKGROUND OFTHE INVENTION This invention relates to improvements in devices forstemming, or closing, the open ends of blast, or shot, holes in miningoperations, and particularly to waterinflatable bags for this purpose,and is a continuationin-part of my co-pending application, Ser. No.81,776 now abandoned.

It is common practice in mining operations to undercut a section of theexposed face of coal, or other material being mined, and to drill aseries of holes above the undercut to receive explosives to break loosethe coal from the vein for transport from the mine. These holes, calledshot holes, are closed by plugs, tamped wadding or other materials, andin other ways, to prevent the explosive from blowing out of the holeswhen fired, and to cause the explosive force to be exerted against theore to be dislodged. Back-firing through the hole is extremely dangerousto workmen, and even with conventional forms of stemming there isconsiderable danger, both from flying debris and from dust. The dust isdetrimental to health and also slows mining operations. Dust and smokeare considered two prime contributors to respiratory impairments such asSilicosis and occupational Pneumoconiosis (Black Lung).

It has been suggested that elongated bags filled with a fluid, such aswater, and tamped into shot holes, will compress longitudinally whileexpanding perimetrically under explosive force and seal shot holes, andthe bursting bag will release the fluid to saturate the dust of theexplosion and prevent its escape into the mine. Water filled bags reducethe violence of the explosion and the dust is held to a minimum. Thebursting of the water-filled bag will extinguish the fire and eliminatethe ignition of any inflammable gas in the shot hole. The bags areusually equipped with a self-closing valve, so that when filled theywill hold the fluid. The valve, however, is in the end of the bag, andoften is exposed across the full end whereby it can be accidentallyopened by a tamping rod in the normal bag seating operation. If thisoccurs, fluid escapes and a dangerous situation arises, for the bag willno longer function as a sealing member, but will blow out when the shotis fired. This condition is present because the fluid pressure withinthe bag tends to force the flexible valve element back toward the bagend where it can become fully exposed.

SUMMARY OF THE INVENTION The general object of the present invention isto provide an improved stemming bag for shot holes having improvedcharacteristics whereby the valve end will not be subject to inadvertentrelease of the bag fluid during use.

A more specific object of the invention is to provide a stemming baghaving a self-closing valve, with means to prevent the valve frombecoming exposed at the bag end, even when the bag is inflated.

Another object is the provision of .a bag of this type having the valverecessed below or within the bag end, and the valve end openingrestricted transversely to limit the area of access to the valve.

A further object is to provide a stemming bag which has a restrictedaccess opening in one end leading to a self-closing valve, with therestricted access forming reinforcements in the valve end portion tostiffen the valve under pressure and assist in maintaining a seal. It isalso an object of the invention to provide a stemming bag withreinforcements at the valve end, so that any rupturing under explosiveforce will occur below the valve end to release the fluid before thevalve end.

has moved from the stemming position, and to thereby direct the releasedwater toward the explosion and breaking ore to dampen the dust.

Still a further object is to provide an improved bag of the foregoingcharacter which is fabricated of a flexible plastic material wherebyopposite sides thereof have different degrees of flexibility so thatwhen filled with the fluid the more flexible bag side is pulled to agreater degree both longitudinally and laterally so that the bagmaterial particularly at the valve end of the bag is pulled downwardlyin a very positive manner to provide a protective shield for the valve.

Yet another object is to provide a bag of the aforementioned type whichis fabricated of a manually stretchable plastic-like material enablingthe bags to be elongated if necessary to reduce their cross-sectionaldimension to facilitate their being placed into irregular size shotholes which may result from use of worn or otherwise non-uniform sizedrill bits.

Other objects of the invention will become apparent from the followingdescription of one practical embodiment thereof, when taken inconjunction with the.

drawings which accompany, and form part of, this specification.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of aplurality of stemming bags integrally, but separably, joined inmanufacture;

FIG. 2 is a perspective view of a pair of overlying plastic sheetsforming the valve elements of the bag structure;

FIG. 3 is a side elevation of the completed bag, parts being broken awayat the center to permit the bag to be shown on a larger scale;

FIG. 4 is a longitudinal section through the bag, taken on the line 4-4of FIG. 3;

FIG. 5 is a perspective view of a liquid inflated bag, an inflating orfilling tube being shown in place in the mouth of the bag;

FIG. 6 is a perspective view of the tube of FIG. 5, fully inflated andwith the tube withdrawn and the valve closed;

FIG. 7 is a longitudinal section through the liquid inflated bag, takensubstantially on the line 7--7 of FIG. 6, with the central portion ofthe bag being broken away;

FIG. 8 is a transverse cross-sectional view through the inflated bag atthe valve area, as viewed on the line 8-8 of FIG. 6; and

FIG. 9 is a side elevational view of the improved stemming bag shown inposition in a shot hole.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings indetail, and first to FIGS. 1 and 2, a plurality of joined stemming bagsand joined valve elements embodying the invention are shown. By makingthe bags in multiples in the form of a sheet from which individual bagscan be removed, the manufacturing process is greatly simplified.

.. W W t The materials used to form the bags consist of two, relativelynarrow, valve-forming strips 1 and two, wide, bag wall-forming sheets 2.For purposes of illustration, valve-forming strips 1 and bagwall-forming sheets 2 are shown of such dimensions as to provide onlythree, joined, valved stemming bags 3, but for practical purposes, tenor more bags may be formed as a unit. The material for both the valvestrips and the wall sheets can be of a vinyl or vinyl-like materialwhich is capable of multi-layered joinder by means of heat seals, or

seams.

The valve-forming strips 1 will be positioned one above the other andsealed, by appropriate heat sealing means, along lines 4, which areU-shaped and provide valve passages 5 between the legs of adjacentU-seams. This joins the strips together and prevents flow of fluidbetween the strips except through the passages 5 when assembled with thebag wall sheets 2.

Joined strips 1, of a suitable length are then placed between the pairof wall-forming sheets 2, with the long edges la of the joined strips 1remote from the heat seams and one edge 2a of the wall-forming sheets incoincidence. This will position the valve elements near one edge of thewall-forming sheets so that the valves will be located at but recessedwithin one end of the completed bags.

The superposed elements 1 and 2 are heat sealed along lines 6 and 7inwardly of, and parallel to, the top edge 8 and the bottom edge 9. Heatseal lines or seams 10 are made longitudinally of sheets 2, parallel toeach other and to the sides of the superposed elements, said seams beingat equally spaced distances, equal to the desired bag width, between theside edges. Near the bag bottom, angular heat seams 11 extend from thelongitudinal seams 10 to the bottom seam 7, with the seams ll divergingfrom opposite sides of each of the seams 10 toward the bottom seam.Similar angular seams 12 extend from each of the longitudinal seams 10toward the top seams 6, but these seams stop short of the top seams 6and interjoin with spaced seams 13 which are parallel to thelongitudinal seams 10, to provide a restricted mouth area 14 leadinginto each valve passage. Of course, care is taken so that these mouthareas are not initially closed by the end seal, such as by interposingan interruptor piece or sheet, not shown, in each of the strategic mouthareas between said sheets 1, before completing the sealing of theextended seam 6 completely across each bag to otherwise join the valveelements 1 to each other and to the bag side walls.

The above-described operations will provide a sheet, or strip, ofcompleted and joined bags, and not only enables a simplifiedmanufacturing procedure to be used, but the resultant product is mucheasier to handle than a plurality of individual bags.

Also, storage is greatly facilitated through the use of flat, multi-bagsheets.

The heat seal lines 10 defining the several bags are made so as to alsoform tear-lines to permit single bags to be removed from the sheetswhile maintaining good longitudinal seals of the bags. Thus, by tearingalong the longitudinal seams 10, individual bags, each with its ownvalve, will be readily obtained as needed, A tapered bottom end can beformed opposite the mouth end of the bag, if desired, by optionallytearing along the angular tear-seal lines 12 and the bottom seam 7.FIGS. 3-9 show the bag 3 as torn from the multi-bag sheet. While theexcess material is very flexible, on occasion the excess material at thebottom may be removed to provide a clean tapered end 15 to betterfacilitate unhampered insertion into a predrilled shot hole 18 (FIG. 9).In FIG. 4, the mouth area 14 is shown spread open for access to thevalve for filling.

The resulting stemming bag 3 has side walls 16, which are parts of theoriginal plastic sheets 2, joined along the side edges by the remainingportions of heat seams 10. An important feature of this improvement bagis the use of two different kinds or types of the flexible vinyl orvinyl-like material for opposite sides of the bags. That is, the vinylmaterial is either of slightly different thicknesses, or if of the samethickness, they are of varying flexibility so that one bag side iscapable of being pulled or more arcuately formed during fluid inflation,primarily in the longitudinal direction. This assures that the endmarginal bag material is pulled downwardly over the ends of the bags toform protective shielding to be discussed in more detail hereinafter.The bag has a lower tapered end 15, closed by the bottom seam 7 andangular seams 11. The top is closed at each side of the mouth area 14,so that the mouth is not over one-half the width of the bag. The mouthpassage flares somewhat below the parallel seams 13 and between theangular seams 12 but only to the points wherein the seams 12 cross theU-shaped valve-forming seams 4, as seen in FIG. 3. From these points,the passage then converges along the curving portions of the U-seamsforming the restricted valve passage 5.

By reason of the mouth and valve construction, the valve passage 5 ispurposely spaced inwardly some distance from the mouth area 14 and topend 8. At the same time, the mouth area is restricted widthwise of thebag to reduce the open area above, and leading into, the valve. Becauseof this, together with the result from the different degrees offlexibility of the bag sides pulling the bag ends 8 and 9 over asprotective flaps, the valve cannot move outwardly into the mouth areaunder internal pressure, and none of the valve structure will be exposedwhen the bag is filled. Therefore it will be virtually impossible toaccidentally contact or open the valve and release the fluid duringnormal operations of placing the bag in a shot hole and tamping it inplace. The restricted mouth serves both as a second shield for the valveand an entrance to the valve which will allow insertion only of a tubeof small enough diameter to enter the valve, but only after thepulled-over protective end flap is straightened out. Larger diameterimplements, such as a tamping rod, cannot reach or penetrate the valvein this improved bag. An approved standard tamping rod is of woodenconstruction, 1 and one-half inch in diameter and about 10 to 12 feet inlength.

In using the device, a tube, such as a tube 17 shown in FIG. 5, isinserted through the mouth 14 and into the valve passage 5, to spreadthe sides of the valve elements to assure free flow of fluid into thebag. Sufficient fluid is put into the bag preferably under some pressureto inflate it to predetermined degree. The tube is then removed. As thetube moves out of the valve passage, the pressure of the fluid withinthe bag, between the bag side walls and those portions of thevalve-forming strips providing the sides of the valve passage, willpress the passage walls into contact with one another to close thevalve. No other sealing is necessary. Although the fluid pressurebetween the bag walls and the valve strip tends to bulge the valveupwardly toward the mouth, the convergent passage between the seal lines12 resist this movement. Thus, the valve remains well down below the bagmouth, unexposed to chance contact with objects which might accidentallyopen the valve. At the same time, the restricted mouth prevents objectsfrom getting into the bag mouth.

Moreover, when the bag is thusly filled, both of the ends have theirmarginal pieces between the seals 6,7 and the respective adjacent ends 8and 9, pulled downwardly as protective end flaps due to the aforestateddifferences in degree of flexibility of the bag sides. Accordingly whena bag is placed into a predrilled shot hole 18, see FIG. 9, and tampedinto place by means of the usual tamping rod, it is apparent that thereis no possibility of the tamping rod entering the bag mouth to contact,and accidentally open, the valve and release fluid. By retaining thelower end marginal flap on the filled bag, it serves to reinforce thatend of the bag and permits the bag to be inserted and tamped at eitherthe top valve end or the opposite end.

The bag material may have a wall thickness of approximately 0.006 inchand is made of a clear vinyl or like material to permit the miners toreadily observe as well as feel the filling fluid during inflation ofthe bags. In order for the valve to work more efficiently, the sheets 1making up the valve components are preferably of only about half thewall thickness, or approximately 0.003 inch, thereby giving them agreater degree of flexibility to more readily close responsive to thepressure of the surrounding fluid. The materials used to comprise thebag sides and having the required characteristics set out hereinabovemay be obtained from various manufacturers, but I have found that theGoodyear Company markets very acceptable types of both the soft andsemi-soft or semi-hard vinyl-like products. More specifically, theGoodyear Company makes a very satisfactory 6 mil (0.006 inch) thick softvinyl under the formulation identification No. Gl6C301l9. A verysatisfactory semi-hard/semi-soft W polyvinylchloride material No. 804 ismanufactured by the Hooker Chemical Company of Hicksville, New

York, and which is preferably also of the 6 mil thickness.

While one practical embodiment of the invention has been disclosedhereinabove, it will be understood that the particular details ofconstruction shown and described are merely by way of illustration, andthe invention may take other forms within the scope of the appendedclaims.

I claim:

l. A shot hole stemming bag adapted to be filled with a non-compressibleliquid during stemming use, said bag comprising in combination, a pairof elongated flexible side panels in overlying position joined alongtheir long side edges by heat seal seams and across their bottoms by aheat seal seam, a pair of flexible valve strips in overlying relationbetween the side panels flush with the top of the side panels and joinedin the side panel side seams, heat seal seams joining the valve stripsalong horizontally spaced lines extending vertically upward from thebottom edges of the valve strips and defining a valve passage betweenthem, heat seal seams inwardly of the side panel side seams extendingdownwardly from the side panel tops and transversing thevalve-passage-defining seams joining the side panels and valve stripsand defining between them an extrance mouth opening to the valvepassage, said entrance mouth being restricted to substantially less thanthe width of the side panel tops, a heat seal seam across the topportions of the side panels, but spaced substantially below said flushaligned top ends of said side panels and valve strips forming apotentially protective end margin or flap, said seam serving to joinsaid side panels respectively to said valve strips transversely of thebag width outwardly of said valve passage, and said seam also joiningsaid valve strips together commencing adjacent opposite sides of saidentrance-mouth-defining seams and extending into each side seam of saidside panels, leaving said valve passage unsealed and free to be openedfor filling use; and one of said side panels being more flexible thanthe other of said side panels so as to induce a pronounced pulling overin one direction of said top end protective end margin or flap when saidbag is liquid filled for stemming use.

2. A shot hole stemming bag as claimed in claim 1 wherein, said heatseal seams that join said valve strips and define said valve passage,extend convergently from said valve strip side edges.-

3. A shot hole stemming bag as claimed in claim 2 wherein, the entrancemouth-defining-heat-seal seams extend from said side panel tops parallelto one another to a distance between said top heat seal seam and saidvalve passage-defining-seams and then diverge downwardly to the pointsof traverse of said valve-passagedefining seams.

4. A shot hole stemming bag as claimed in claim 3, wherein bottomportions of the sides of the side walls converge downwardly to provide abag having a tapered end opposite the entrance mouth.

5. A shot hole stemming bag as claimed in claim 4 wherein, the side wallpanels and valve strips are of a transparently clear vinyl material.

6. A shot hole stemming bag to be filled with a liquid and inserted intoa shot hole during use, comprising in combination, an elongated flexiblematerial body having opposite side panels with sides, bottom and top, aflexible self-closing valve attached to said side panels within the bodyadjacent, but spaced inwardly from said top leaving a top marginal pieceof material to constitute a potential valve-protective flap wheninserted bottom-end first, said top of said bag being closed from theside edges inwardly to an entrance mouth of restricted width opening tothe valve; one of said opposite side panels being more flexible than theother of said opposite side panels so as to induce a pronounced pullingin one direction of said top marginal valveprotective flap responsive tosaid bag being filled with liquid for shot stemming use.

7. A shot hole stemming bag as claimed in claim 6 wherein, the entrancemouth width is not more than one-half the width of the bag top.

8. A shot hole stemming bag as claimed in claim 7 wherein, the valveincludes a passageway opening to the bag body, and there is a throatbetween the entrance mouth and the valve passageway diverging from themouth toward the passageway.

9. A shot hole stemming bag as claimed in claim 6 wherein, the bottom ofthe bag body tapers downwardly and terminates in a marginal bottom flapwhich also is pulled in said same one direction as said top marginalvalve-protective flap for said same reason, and thereby constitutes aprotective bottom end flap to re- 3,806,025 7 8 inforce the bottom-endportion of said bag during 10. A shot hole stemming bag as claimed inclaim 6 valve-end-first insertion into a shot hole with the aid ofwherein, the bag body and valve are of a transparently a conventionaltamping tool pushing against said botclear vinyl material. tom end ofsaid bag.

1. A shot hole stemming bag adapted to be filled with a noncompressibleliquid during stemming use, said bag comprising in combination, a pairof elongated flexible side panels in overlying position joined alongtheir long side edges by heat seal seams and across their bottoms by aheat seal seam, a pair of flexible valve strips in overlying relationbetween the side panels flush with the top of the side panels and joinedin the side panel side seams, heat seal seams joining the valve stripsalong horizontally spaced lines extending vertically upward from thebottom edges of the valve strips and defining a valve passage betweenthem, heat seal seams inwardly of the side panel side seams extendingdownwardly from the side panel tops and transversing thevalve-passage-defining seams joining the side panels and valve stripsand defining between them an extrance mouth opening to the valvepassage, said entrance mouth being restricted to substantially less thanthe width of the side panel tops, a heat seal seam across the topportions of the side panels, but spaced substantially below said flushaligned top ends of said side panels and valve strips forming apotentially protective end margin or flap, said seam serving to joinsaid side panels respectively to said valve strips transversely of thebag width outwardly of said valve passage, and said seam also joiningsaid valve strips together commencing adjacent opposite sides of saidentrance-mouth-defining seams and extending into each side seam of saidside panels, leaving said valve passage unsealed and free to be openedfor fiLling use; and one of said side panels being more flexible thanthe other of said side panels so as to induce a pronounced pulling overin one direction of said top end protective end margin or flap when saidbag is liquid filled for stemming use.
 2. A shot hole stemming bag asclaimed in claim 1 wherein, said heat seal seams that join said valvestrips and define said valve passage, extend convergently from saidvalve strip side edges.
 3. A shot hole stemming bag as claimed in claim2 wherein, the entrance mouth-defining-heat-seal seams extend from saidside panel tops parallel to one another to a distance between said topheat seal seam and said valve passage-defining-seams and then divergedownwardly to the points of traverse of said valve-passage-definingseams.
 4. A shot hole stemming bag as claimed in claim 3, wherein bottomportions of the sides of the side walls converge downwardly to provide abag having a tapered end opposite the entrance mouth.
 5. A shot holestemming bag as claimed in claim 4 wherein, the side wall panels andvalve strips are of a transparently clear vinyl material.
 6. A shot holestemming bag to be filled with a liquid and inserted into a shot holeduring use, comprising in combination, an elongated flexible materialbody having opposite side panels with sides, bottom and top, a flexibleself-closing valve attached to said side panels within the bodyadjacent, but spaced inwardly from said top leaving a top marginal pieceof material to constitute a potential valve-protective flap wheninserted bottom-end first, said top of said bag being closed from theside edges inwardly to an entrance mouth of restricted width opening tothe valve; one of said opposite side panels being more flexible than theother of said opposite side panels so as to induce a pronounced pullingin one direction of said top marginal valve-protective flap responsiveto said bag being filled with liquid for shot stemming use.
 7. A shothole stemming bag as claimed in claim 6 wherein, the entrance mouthwidth is not more than one-half the width of the bag top.
 8. A shot holestemming bag as claimed in claim 7 wherein, the valve includes apassageway opening to the bag body, and there is a throat between theentrance mouth and the valve passageway diverging from the mouth towardthe passageway.
 9. A shot hole stemming bag as claimed in claim 6wherein, the bottom of the bag body tapers downwardly and terminates ina marginal bottom flap which also is pulled in said same one directionas said top marginal valve-protective flap for said same reason, andthereby constitutes a protective bottom end flap to reinforce thebottom-end portion of said bag during valve-end-first insertion into ashot hole with the aid of a conventional tamping tool pushing againstsaid bottom end of said bag.
 10. A shot hole stemming bag as claimed inclaim 6 wherein, the bag body and valve are of a transparently clearvinyl material.